High pressure radial piston hydraulic pump or motor



y 1935. E. K. BENEDEK 2,006,880

HIGH PRESSURE RADIAL PIS TON HYDRAULIC PUMP OR MOTOR Filed Oct. 1, 19513 Sheets-Sheet 1 4! 55 INVENTOR [if/f A. BEA/05K A TTORN July 2, 1935.E. K. BENEDEK 6,880

HIGH PRESSURE RADIAL PISTON HYDRAULIC PUMP OR MOTOR Filed Oct. 1, 1931 sSheets-Sheet 2 9L AMORNZ? y 1935- E. K. BENEDEK 2,006,880 0 HIGHPRESSURE RADIAL PISTON HYDRAULIC PUMP OR MOTOR Filed Oct. 1, 1931 sSheets-Shet s Hllflllllllllllm.

V ummw //Mm|m|mw// 1201* /r. Bnvmnr Patented July 2, 1935 UNITED STATESPATENT OFFICE HIGH PRESSURE RADIAL PISTON HY- DRAULIC PUMP OR MOTOR ElekK. Benedek, Mount Gilead, Ohio, assignor to The Hydraulic PressManufacturing Company, Mount Gilead, Ohio Application October 1, 1931,Serial No. 566,381 6 Claims. (o1. 103-161 and compact in constructionand yet is capable of producing a higher pressure and more uniform,variable output when operating as .a pump, or when operating as amotor,-is capable of producing materially greater starting torque due tothe many points at which propelling force is applied during a singlerevolution and is thus better adapted for starting at creeping speeds,than is possible in pumps or motors of like types of which I am atpresent aware Pumps of conventional forms of this type usually arelimited to the use of five or seven pistons or plungers because thecrossheads which are found necessary in connecting the pistons with theeccentric or impeller are-more or less large and complicated inconstruction and require the employment of cylinder barrels of greaterlength than are desirable or would otherwise be necessary. These typesof pumps are'capable only of non-uniform fluctuating delivery and cannotbe used efficiently for many purposes, say for example in grinding,drilling and threading machines in which it is absolutely essential thatthe rate of feed be kept at a predetermined constant value.

Furthermore, conventional forms of pumps of the types stated usuallyemploy rotating cylinder barrels in the bores of which pistons are.caused to reciprocate because of their connection, through the medium ofcrossheads, with an eccentric or impeller adapted to rotate with thebarrel about an axis disposed eccentrically with relation to the axisof'rotation of the barrel, and, thus serving as rotation impartingelements, the pistons are necessarily subjected to lateral strains ortorque which results in much unnecessary friction and wear andmaterially reduces the life of the pump structure.

Having in mind remedying the defects above enumerated, I have designedthe improved structure herein disclosed with the object of providing apump or motor in which novel means other than pistons and crossheads areemployed to cause the cylinder barrel and the eccentric or impeller torotate together, thus entirely relieving the pistons of the objectionalstrains to which they are subjected in the pumps and motors abovereferred to. I

Another object of the invention is to provide in a pump or motor novelpiston "construction and arrangement enabling efiicient employment of anunusually large number of pistons in an unusual- 'driven shaft, beingshown in elevation.

ly small space and in a manner assuring, high pressure output at auniform rate when used as a pump, and enabling easy starting at creepingspeeds when used as a motor, due to the large number and smallseparation of points where 5 power is applied during a singlerevolution.

Other objects will in part be obvious and in be pointed out hereinafter.Y

To the attainment of the aforesaid objects and ends the invention stillfurther resides in the novel details of construction, the combinationand arrangement of .parts, all of whichwill be first fully described inthe following detailed description and "then particularly pointed out inthe appended claims; reference being had to the accompanying drawings inwhichz- Figure 1 is a horizontal section taken through the axis of apump or motor. embodying my invention, the pintle and a portion of adriving or part Figure 2 is a vertical cross section taken on the line2-2 on Figure 1.

Figure 3 is a detail vertical cross section taken on the line 3-3 ofFigure 1.

Figure 4 is a detail vertical cross section taken on the line 4-4 onFigure 1.

Figure 5 is a detail vertical cross section taken on the line 5-5 onFigure 1 Figure 6 is a central longitudinal sectional view of thecylinder barrel.

Figure 7 is a right-hand end elevation of the cylinder barrel shown inFigure 6.

Figure 8 is aninner face view of one of the supplemental coupling rings.I

Figure 9 is anouter face view of the coupling ring shown in Figure 8.

Figure 10 is a vertical cross section'of the coupling ring shown inFigures 8 and 9 V Figure 11 is an end elevation of the eccentric orimpeller ring. 40

Figure 12 is a longitudinal section of the eccentric or impeller ring.

Figures 13 and 14 are inner and outer face. views, and

Figure 15 a vertical cross section of one of the main coupling rings.

Figures 16 and 17 are side elevation and invertedplan views of' one ofthe piston elements.

Figure 18 is'a side elevation and part section of a modified form ofpiston.element, and

Figure 19 is atop plan view of the piston'element shown in Figure 18. gt

In the practical development of the invention I provide a pump casing inthe nature ofan annular ring 5 having an integral supporting 55 baseportion 6, horizontally and diametrically oppositely disposed bossesprovided with guide bores 1 and upper and lower slide guide pads 8. Oneend of the casing is closed by a wall 9 and the other end thereof isformed open but is normally closed by an end cover plate l which issecured as at H to the casing ring 5.

The cover plate is provided with an annular film bearing wall ring l2opposing a similar like designated ring formed on the casing wall 9 andis bored as at l3 to receive the enlarged head 14 of a pintle I5, saidhead being secured in the bore by a key IS.

The pintle I5 is provided with an upper pairl1 and a lower pair l8 oflongitudinal passages. The upper pasages l1 communicate through a commonport l9 in the pintle head M with a combined inlet and outlet portformed in the hub of the cover plate I0 and with three upper cutouts 2|disposed in spaced relation along the pintle IS. The lower passages l8similarly communicate through a common port 22 in the pintle head with acombined inlet and outlet port 23 in the cover plate hub and with threelower cutouts 24 disposed in spaced relation along the pintle and eachin the same plane with an associated upper cutout 2|.

The passages l1 and I8 terminate in the free end of the pintle beyondthe cutouts 2| and 24 and attheir other ends, where they pass throughthe pintle heads l4, they are plugged as at 26. It will be observed byreference to Figure 2 of the drawings that the formation of the cutoutsprovides for solid bridge portions 21 which separate the upper and lowercutouts and provide cylinder bore cutoffs.

The end wall 9 of the casing is provided with an axial hub extensionwhich is bored axially from its respective ends to form a shoulder 28and annular-recesses at its respective ends and separated by saidshoulder, the recess at the inner end serving to accommodate a shaftreceiving film-bearing member 29, andthe recess at the outer end servingto accommodate a gland packed as at 30 and the gland head 3| of which issecured as at 32 to said hub extension.

A driving or driven shaft 33 is rotatably mounted in the bearingsprovided therefor in the hub extending from the casing wall 9 and isequipped with a head 34 which is rotatable in the pump casing and issecured as at 35 to a cylinder barrel 38 equipped with an axial bore tofit and have rotative bearing on the pintle l5. The cylinder barrel 38is provided with a plurality, of sets of radial cylinder bores 31. Inthis particular disclosure I have shown three such sets of bores andeach set comprises five radial bores all of which are disposed in acommon plane intersecting one upper and lower pair or set of pintlecutouts 2| and 24. The sets of bores are arranged in individual phaserelation so that each bore will lie in a distinct radius, thus providingfifteen distinct bore radii disposed equidistantly about the common axisof the cyl inder barrel and pintle.

-An eccentric and impeller ring 38 surrounds the "cylinder barrel inspaced relation, and surrounding this ring 383s a shifter ring 39 inwhich the impeller or eccentric ring 38 is afforded rotative bearing ina high pressure oil film as indicated at 40. This film bearing may be'of any suitable structure, but is preferably .constructed in accordancewith the disclosure in co-pending application Serial No. 557,888, filedAugust 18, 193i. .Shifter rods' 4| are slide guided in the casing bores1 and are secured as at 42 to the shifter ring 39 so that when they aremoved longitudinally by any suitable control means (not shown) theshifter ring will be shifted in a straight line coincident with animaginary line drawn through the axis of the pintle and centrallythrough the bridge portions 21 thereof because of the guiding functionof the casing pads 8 and the coacting pads 43 with which the shifterring 39 is provided.

The eccentric or impeller ring 38 is provided with a plurality of tonguereceiving grooves 44 in each end edge thereof and the cylinder barrel 36is equipped with similar tongue receiving grooves 45 which, however, aredisposed normally with relation to the grooves formed in the ring 38. Acoupling ring is disposed at each side of the casing and each such ringis formed compositely of a main ring 46 and a supplemental ring 41secured to the main ring as indicated at 48. Each main ring 46 isequipped with a plurality of tongues or keys 49 which project into andslide freely in the grooves 44 in the ring 38, and each supplementalring 41 is equipped with a plurality of tongues or keys 50 which aresuitably positioned for projecting into and sliding freely in thegrooves 45 formed in the cylinder barrel.

The tongue and groove equipments 44, 45, 49 and 50 of the rings 38, 46and 41 and the cylinder barrel 36 provide universal coupling for theeccentric or impeller ring 38 and the cylinder barrel 36, causing themto rotate together regardless of the degree of eccentricity to which thering 38 has been shifted. It is to be understood, of course, that duringactive operation of the device as a pump or motor the cylinder barrelrotates about the axis of the pintle and the eccentric or impellerrotates about an axis spaced from or bearing eccentric relation to saidpintle axis.

A piston 5| is reciprocable in each cylinder bore 31 and includes acylindrical portion to fit the respective bore and a small flat headextension which projects beyond the bore and serves as a retaining meanslimiting inward movement of the piston and yet is so small that thedegree of its projection beyond its respective bore, and which might besaid to limit the number of sets of piston and bore equipments whichcould be arranged along a given cylinder barrel length, is negligibleand in no wise hinders the degree of compactness possible in my improvedpump or motor.

The fiat heads of the pistons frictionally engage the inner wall of theeccentric or impeller ring 38 so that during half a rotation of thecylinder barrel said wall will serve to limit the outward travel of thepistons and during the remainder of the rotation said wall will engagesaid piston heads and force them radially inward. If desired the pistonheads may be provided with ball seats 53 and anti-friction balls 54disposed in the seats for engagement with the eccentric or impellerwall.

The structure hereinbefore described, is designed for use as a pump ormotor, and when used as a pump is capable of delivering fluid at hghpressure and at a uniform rate. When so used the pump is preferablysupercharged from an ordinary low pressure pump (not shown) and willbuild up the desired high pressure and deliver the fluid in a smoothnon-fluctuating manner.

This construction of pump will be found particularly desirable for usein feeding machine tools such as grinding machines, drilling'machines orthreading machines in which it is very important to keep the rate of thefeed at a predetermined constant value.

In the conventional "forms of pump now in use and in which five plungersusually are provided, there are a maximum of two or three pis-' tons onthe pressure'side at any given time delivering two or three harmonicimpulses at one time to the feed cylinder. It is obvious that in case oftwo pistons, the impulses are too great and also the slip variation is,even under normal conditions, not permissible. Such difficulties can beovercome only in high pressure application by multiple plunger typepumps such as I have disclosed 1 herein. When the number of plungersdelivering atlzt given instant to a feed cylinder is about six or seven,it is obvious that the fluc- 'tuation in the volume of delivery, as wellas the fluctuation of the resulting flow, is less in the proportion ofthe greater number of plungers.

In Figure 2 of the drawings I have shown the eccentric or impeller ringshifted to the neutral position in which no outputof fluid will beeffected. When the ring 38 is shifted to the right it will rotate aboutan axis disposed eccentrically with reference to and at the right of thepintle axis and the pistons in the upper half of the cylinder barrelwill be moved outwardly and therefore will suck fluid through the upperports and passages 20, I9 and I1 and the pistons in the lower half ofthe cylinder barrel will be moved inwardly and will expel fluid smoothlyat high pressure and uniform rate through lower ports and passages I8,22 and 23. By shifting the eccentric or impeller ring and thus varyingthe eccentricity thereof the output of the pump may be varied, and byshifting the axis of said ring to the opposite side of the pintle axisthe pump may be reversed in a manner well known in this art.

As hereinbefore stated the structure which I have dsclosed hereinoperates very efliciently as a motor and enables starting of the motoreasily at creeping speeds, for reasons previously disclosed. The presentdesigns of hydraulic motors of which I am aware have the followinglimitations:

1. Limited number of pistons. The maximum number of plungers possiblepractically in presentccnstructions is five to seven, which means thatin the working chamber of the motor three or four at most, and posthedriving torque required from the motor at any given time. It is evidentthat the resultant torque of two pistons is non-uniform and fluctuating,especially if one of the pistons has some unusual leakage. torque isleft entirely to the effort of a single plunger which fact shows that insuch a phase the motor would be inadequate to furnish sufficientstarting torque for its requirement.

2. The locking tendency of the pistons in the dead center position.

Let us assume that the above mentioned two or three working pistons areon the expansion side of the motor and that one plunger is in its deadcenter at the beginning of the fluid expan In that case, theresultantnumber of pistons in'present conventional constructions isimpossible due to the fact that in these constructions the piston unitshaving special crossheads which limit the number of pis-.=

tons which can be accommodated. A multi-row arrangement of the pistonsin such constructions is almost impossible due to the fact that thecrosshead masses which they employ would cause undesirable unbaflancedforces in the unit and also would make the construction too expensive.3. The impossibility of exerting high starting torque in above mentionedconstructions by using a piston unit as a coupling element between theimpeler or eccentric unit and the driven unit or cylinder barrel of themotor. No matter what is the contructive solution for transmitting thedriving torque to the rotor of the motor by pressure of the fluid onthe'pistons thus coupled, it will be evident that the fluctuationof theload on the motor shaft would cause tangential forces on the pistonunits and therefore it would be subjected to wear and strain which wouldmaterially affect the life of the tures of my device employed as a motorcan be summarized as follows:

' (a) Elimination of complicated, space consuming crossheads.

Because my hydraulic motor does not require any crosshead to exertsucking effort, therefore the omission of crossheads enables me to builda multiple row piston motor in a very limited space.

expensive,

The reason for this is that my motor pistons do not require anycrosshead. The pressure fluid expands duringthe inlet period, therebypushing the pistons outward toward the eccentrically located rotor, andduring the exhaust period the rotor pushes the pistons inwardly therebyforcing the fluid into the exhaust line. It should be easy to understandthat during the whole cycle of expansion and exhaust the force on thebottom of the piston always tends to push'the pistorrtoward the rotor,thus the piston always will be kept in contact with the rotor withoutany need for crosshead.

(b) The locking tendency of the pistons is eliminated by the greatnumber of pistons active at a given interval.

In my present invention the motor is shown as having pistons or plungersarranged in three series of five each, in place of the five plungers,whereby the fluctuation of the resultant torque isthree times less, andgenerally speaking ntimes as low as inabovementioned construction.Experimental results of present conventional forms of motors show thatdue tothis locking tendency the'starting torque ,of the motor ispractically zero and even at creeping speed the torque is below 50% ofthe theoretical torque of '1 ]able number of plungers for attainingthe'desired smoothness in starting.

By considering the fact that only one plunger can-be in locking deadcenter position at any given time whereas the rest of the plungers, saysix, in a' fifteen plunger motor, are exerting starting torque, it isevident that excluding the frictional resistance of the motor, onlyoneseventh of the total theoretical torque is lost by the fact that onepiston is in the dead center, and besides the exerting thereof ofpositive braking effort. By braking effort I mean the fact that theplunger in the dead center, under fluid pressure, positively acts as abrake. Six of the cylinders which are working at a certain torque-radius easily overcome the locking effort of the brake piston and thuscarry the load on the motor shaft with a fluctuation characteristic, sayonesixth, or in terms of efficiency it can be seen easily thatapproximately only 16% of the theoretical torque causes fluctuation evenif we assume that the pistons exert equal torques in every position ofthe expansion stroke. Actually, however, the torque radius of eachpiston changes according to a sine curve, therefore the loss around thedead center is not so great in the theoretical torque, but the loss iscaused by the fact that the piston exerts braking of its maximum torquecapacity, and this in unavoidable. To summarize the facts, it is evidentthat the greater the number of pistons, the greater starting torque canbe obtained and a more uniform running torque can be maintained in ahydraulic motor.

(d) The application of a coupling (mechanical) between motor cylinderand motor eccentric.

An eflicient form of universal coupling has been applied at both ends ofthe cylinder and eccentric unit in order to exert the driving torquebetween the two elements. Therefore, any participation of the pistons intransmitting the torque is entirely eliminated. The hydraulic fluidpressure 'on the bottom of the pistons exerts an eccentric force aroundthe center of rotation of the eccentric and therefore it causes theeccentric to rotate. The resultant of all the piston forces exerts atorque around the center line of the eccentric and ,will rotate theeccentric around that center line. This rotating force from theeccentric will be carried over to the cylinder unit by the universalcoupling, which cylinder unit is secured to and imparts rotation to themotor shaft and thus gives off the work of the motor.

' Should the eccentric have been coupled to the cylinder by the pistons,naturally the torque of the eccentric would be transmitted to the rotorshaft by the pistons and this would cause more or less rapid wear on thepistons and cylinder walls.- By the elimination of friction losses byabove mentioned mechanical coupling I claim that the efliciency of themotor has been improved considerably.

In present commercial motor practice, the main demands upon the motorare high starting torque, high running torque and high static orpotential torque. All these requirements are demanded almostsimultaneously but none of them has been satisfied up to the presenttime. I claim that my hydraulic motor can meet all above mentioneddemands.

- The stroke of the pistons of my motor can be fixed or can be made.adjustable by providing means for varying the separation of the primaryand secondary rotors, as is well known in the art. However, theemployment-of a variable stroke pump to operate the motor usuallyobviates the need for a variable stroke motor. The number of plungerswill determine the starting characteristics of the motor, and because inmy construction the number of plungers is not limited; therefore I claimthat I have a motor adapted for any requirement for uniform runningtorque and smooth starting.

When my device is operating as a motor, the high pressure fluid entersand passes through a selected group of the ports and passages 20, I9 andIT, or 23, 22 and I8, and through the associated pintle cutouts 2| or 24into the registered cylinder barrel bores 31. This high pressure fluidexerts hydraulic pressure on the bottom of the associated pistons andthis pressure is distributed through the pistons to the wall of theeccentric or impeller 38 causing it to rotate together with the cylinderbarrel and the driven shaft attached to the end thereof. The moment thepiston reaches the horizontal or dead center position it will be passingone of the bridge portions of the pintle and approaching the exhaustside of the motor chamber where it will be forced radially inward by theengaging impeller wall causing the theretofore working fluid to beexpelled from the motor through the associated group of cutoutsdischarges and ports.

Thus it will be seen that the pressure fluid enters the motor, engagesthe pistons therein and delivers work to the rotor shaft giving up itspower through the period of expansion. The pistons having finishedtheir; working stroke then act to expel fluid from the motor.

There is an expansion period for the fluid down to about atmosphericpressure if there is no resistance in the exhaust line, then an exhaustperiod during which the fluid is forced out of the pump. It will be seenthat the fluid in the motor always is under pressure. There is nosuction period which would cause partial filling of the individualcylinders. The motor preferably functions as a 100 per cent superchargedmetering pump which discharges a uniform amount of fluid per revolution.The amount of fluid is determined by thefsize of the cylinders and thepiston stroke theoretically, and practically by the cavitation caused bythe restricted passages of the pressurefluid which tends. to fill outthe individual cylinders while they are in communication with thepressure chamber of the motor. While there is limited time for thispurpose. ample passages are provided in the pump so that the individualcylinders will be completely filled out with pressure fluid without theconsiderable loss of pressure or velocity head.

From the foregoing description taken in connection with the accompanyingdrawings, it is thought that the novel details of construction, themanner of use and the advantages of my improved pump or motor will bereadily apparent tothose skilled in the art to which it relates.

I claim:

1. A hydraulic pump or motor comprising a primary rotor, a secondary;rotor in spaced relation thereto, a plurality of radially disposedcylinders in said primary rotor, pistons reciprocable in said cylindersand operatively connected to said secondary rotor, and-universalcoupling and driving meansconnecting the corresponding opposite ends ofsaid rotors and having multiple inter-engaging portions adaptedsimultaneously to transmit power therebetwcen and to brace said rotorsrelative to one another whereby to provide supporton the opposite sidesof said cylinders against the unequal stressesset up in the radial tionthereto, universal coupling and driving means connecting thecorresponding opposite ends of said rotors and having multiple inter--engaging portions adapted simultaneously to transmit power therebetweenand to brace said rotors relative to one another, and a plurality ofpistons reciprocably mounted in said primary rotor and havingcircumferential sliding engagement with s'aid'secondary rotor, saidpistons be- .ing disposed in a plurality of spaced banks along the axisof said primary rotor.

3. A hydraulic pump or motor comprising a primary rotor, a secondaryrotor in spaced relation thereto, universal coupling and driving meansconnecting the corresponding opposite ends of said rotors and havingmultiple interengaging portions adapted simultaneously to transmit powertherebetween and, to brace said rotors relative to one another, and aplurality of rocable in said cylinders and operatively connected to saidsecondary rotor, and universal coupling and driving means connecting thecorresponding opposite ends of said rotors and having multipleinter-engaging portions adapted simultaneously to transmit powertherebetween and to brace said rotors relative to one another, saidcoupling and driving means comprising a coupling ring and co-operatingsets-of multiple tongues and grooves respectively disposed among theprimary rotor, the secondary rotor and the coupling ring, whereby toprovide support on the opposite sides of said cylindersagainst theunequal stresses set up in the radial reciprocation of said pistons.

5. In a hydraulic pump or motor,-the combination of a rotatable primaryrotor, a plurality of cylinder and piston units therein, a rotatablesecondary rotor, and universal coupling devices interconnecting theprimary and secondary rotors to cause them to rotate in unison aboutseparated axes, said coupling devices comprising a coupling ringdisposed on each side of the secondary rotor with rotative bearing onthe walls of the housing, and cooperating sets of tongues and groovesdisposed normally relative to one another and distributed amongthecoupling ,connected by universal coupling devices; said couplingdevices comprising a coupling ring disposed on' each side of thesecondary rotor with rotative bearing on the walls of the housing andcooperating sets of tongues and grooves disposed normally relative toone another and distributed among the coupling rings and the primaryand'secondary rotors, and a shifter ring having provision for forming a highpressure film bearing in which the secondary rotor has rotative hearing,said film bearing and said universal coupling devices being fed withlubricant from the lubricant bath in the housing.

ELEK K.'BENEDEK.

